<?php 
	$str = 123456;
	//原始
	echo $str,"<br/>";
	
	$str_en = encrypt('henly',$str);
	//加密后
	echo $str_en."<br/>";

	$str_de = decrypt('henly',$str_en);
	//解密后
	echo $str_de;


	//加密
	function encrypt($key,$plain_text){
		$plain_text = trim($plain_text);
		$iv = substr(md5($key),0,mcrypt_get_iv_size(MCRYPT_CAST_256,MCRYPT_MODE_CFB));
		$c_t = mcrypt_cfb(MCRYPT_CAST_256,$key,$plain_text,MCRYPT_ENCRYPT,$iv);
		return trim(chop(base64_encode($c_t)));
	}


	//解密
	function decrypt($key,$c_t){
		$c_t = trim(chop(base64_decode($c_t)));
		$iv = substr(md5($key),0,mcrypt_get_iv_size(MCRYPT_CAST_256,MCRYPT_MODE_CFB));
		$p_t = mcrypt_cfb(MCRYPT_CAST_256,$key,$c_t,MCRYPT_DECRYPT,$iv);
		return trim(chop($p_t));
	}